Conventional gallium nitride (GaN) high-electron mobility transistor (HEMT) structures are typically fabricated with a ternary or quaternary barrier layer. The barrier layer may be composed of indium (In), aluminum (Al), and/or gallium (Ga), for example, InxAlyGa1-x-yN, where x and y indicate relative concentrations. The barrier layer may be epitaxially grown on a GaN channel/buffer layer. The barrier layer induces charge near the barrier/channel interface due to spontaneous polarization and/or piezoelectric effects. The density of this charge is strongly dependent on the composition of the barrier material and the surface condition. In some cases a large lattice mismatch stress must be accommodated to achieve the high charge densities needed for high performance device fabrication. These mismatch stresses, and high surface sensitivity, can lead to reliability limitations for such devices.